are you saying it clicks and wont crank? or it clicks and cranks over and just wont start?

well to start i wouldnt think that a fully charged battery should drop that many volts just turning on switch

so it sounds to me like you have a dead short or a loose or bad connection somewhere for that matter and it could be the coil by it getting unreasonably hot but could also be something else

my best though is either the coil or the battery has just went bad, i had one in my car one day that had never give any sign of going bad and i was backing out of the driveway and the just died and as it turned out the battery just shorted out internally

X2...Ive had several batteries develop internal shorts over the years. Clean up all your connections & make sure they are tight. Negative side of coil goes to distributor. This wont cause short but will deliver better spark.

not trying to dispute your word dbn but it will short out an elctronic or at least ive seen it happen at least twice however it may work either way with points im not sure on that but you are correct that the neg goes to dist. and pos. goes to keyed power source

Ive never hooked a coil up backwards on an electronic before so I dont know the consequences. I only tossed that in there since having the coil wired backwards causes very weak spark with points & makes it tough to start with a weak battery. I wonder if having it backwards with an electronic ignition would make the coil heat up like he described?